Formatting an ‘unformattable’ flash drive

“Using the Windows Defender Offline (WDO) installer ended in repeated drive-formatting failures. I finally solved the problem by running Diskpart on the USB drive, as described in a TechNet Blogs post.

“It’s a pity that the WDO installer isn’t written to do this automatically!”

Yes, the WDO installer is fairly basic. There are many types of flash-drive partitions and formats, and it will stumble on some of them.

There are, in fact, over 100 different ways that drives can be partitioned and formatted. For example, a drive might be partitioned with MBR, EBR, or GPT (more info). It could be formatted with some version of FAT (e.g., FAT, FAT12, FAT16, FAT16B, FAT16X, FAT32, or FAT32X), with NTFS, or with any of the various Linux formats. Finally, there are the sector-size and emulated-drive-geometry options.

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